what are the rpms at when you say yourer going mph it might be stuck in nd if its accelerating very slowly and maxes out at a fairly low speed did you check the tranny fluid many cars have a limphome mode that locks the tranny in a certain gear and lets you still drive it albeit at a very low speed just enough to let you go home without doing more damage to the tranny do you have a cel it could be something as simple as a computer glitch or it could be as complex as a fried transmission which i doubt can you force the car into rd or th if so what does it do